Monitoring Fish Passes

River Lochay

In the River Lochay near Killin, SSE refurbished three fish passes which were installed in the 1960s to allow salmon easier access around small waterfalls. These fish passes had suffered deterioration since originally installed and there was concern that they were no longer capable of passing fish effectively.

The Tay District Salmon Fisheries Board, which was a partner in the CASS project, agreed to monitor the effectiveness of this work. The Tay Foundation has since been supporting this work which consists of annual electrofishing surveys in the upper Lochay to determine whether salmon are using the passes in increased numbers.

Results for the early years are presented on pages 21 to 27 of the attached report. These results indicate that the improvement works have indeed resulted in more salmon spawning successfully in the upper Lochay than immediately beforehand.

River Gaur

The River Gaur is the westernmost tributary of the River Tummel, rising on Rannoch Moor and flowing into the west end of Loch Rannoch. A hydro dam on the river is bypassed by the UK's longest pool-step fish pass. However, at the head of the fish pass there is a Borland fish lift to enable fish to exit easily into the loch above.

In former times this lift had been fished manually, but after the station was automated years ago, the lift ceased to operate. At that time there were significant smolt passage issues lower down the Tummel system and there was little concern for salmon as far upstream as Gaur.

However, in the early 2000s it was found that salmon were recolonising the River Gaur downstream of the dam following improvements in smolt passage that had taken place further downstream in the 1980s. The decision was taken therefore by SSE to automate the borland left when Gaur power station was refurbished in the early 2000s. Once this was completed, it was then found that there were difficulties in maintaining the flow in the fish pass at certain stages of the lift cycle. It was to overcome this problem that a regulating valve was inserted as part of the CASS project.

As in the case of the Lochay passes, the Tay Foundation has supported monitoring work upstream of the dam to determine whether the greatly improved fish pass arrangements have worked or not. Results for the early years are presented on pages 10 to 15 of the attached report. These results indicate that the improvement works have indeed resulted in more salmon spawning successfully in the upper Gaur but it has still a long way to go to be fully populated.